BLACK-FOOTED FERRET

Imagine conservationists’ delight when a small population of black-footed ferrets, which were extirpated from Canada’s Prairies by the 1930s and assumed extinct everywhere in the 1970s, was rediscovered on a Wyoming ranch in 1981. Within a few years, captive breeding programs were redistributing these bandit-masked members of the weasel family, with 35 released into Saskatchewan’s Grasslands National Park in 2009. Their survival depends on robust colonies of their main food, black-tailed prairie dogs. Today there are a dozen or more adult black-footed ferrets living and breeding in Canada, so the population is still far from stable.

NEWFOUNDLAND MARTEN

Another troubled member of the weasel family, this subspecies of American marten is found only in Newfoundland, where it once lived in tree branches throughout the province’s forests. After centuries of being trapped for its pelt, however, the government stepped in to make commercial harvesting of the species illegal. That was in 1934, but the animal’s numbers continued to decline, probably because of habitat fragmentation from logging. After hitting a low of fewer than 300 in 1995, between 400 and 850 are now thought to be breeding in five isolated subpopulations in Newfoundland.

KIRTLAND’S WARBLER

This rarest of North America’s songbirds has been confirmed breeding in Canada only a few times: near Barrie, Ont., in 1945, and at Canadian Forces Base Petawawa in 2007 and 2008. The majority of its range lies in Michigan, though it may once have been a regular in Ontario. Kirtland’s warbler is fussy — after wintering in the Bahamas, it returns each May to nest, but strictly in large stands of young Jack pine. Human suppression of natural forest fires prevented the renewal of these forests, and the species hit an all-time low of about 170 males in the 1970s. Habitat management in Michigan has since helped them rebound to between 1,500 and 2,000 breeding pairs, so Canadians could soon be seeing more of the warbler.